<!DOCTYPE html>
<html lang="en">

<head>
  <meta charset="UTF-8">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <!-- 引入Vue -->
  <script type="text/javascript" src="../js/vue.js"></script>
</head>

<body>
  <div id="root">
    姓：<input type="text" v-model="firstName"><br /><br />
    名：<input type="text" v-model="lastName"><br /><br />
    全名:<span>{{fullName()}}</span><br /><br />

  </div>
</body>
<script type="text/javascript">
  Vue.config.productionTip = false; //阻止vue在启动时产生产提示
  let vm = new Vue({
    el: '#root',
    data: {
      firstName: '张',
      lastName: '三'
    },
    methods: {
      // 数据修改每次重新调方法,效率不高
      fullName() {
        // this是vm
        return this.firstName + '-' + this.lastName
      }
    }
  })
</script>

</html>